【kubernetes/k8s源码分析】calico typha源码分析

迈不过友情╰ 2023-06-16 15:55 95阅读 0赞

# 描述 #

Typha：在节点数比较多的情况下，Felix 可通过 Typha 直接和 Etcd 进行数据交互，不通过 kube-apiserver，既降低其压力。（有待验证）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70][]

引入网上他人图片，恩画的非常好

*  BGPClient(BIRD)：把 Felix写入 kernel的路由信息分发到当前 Calico网络，确保 workload 间的通信
 *  BGPRoute Reflector(BIRD)：大规模部署时使用，通过一个或者多个 BGPRoute Reflector 来完成集中式的路由分发；后端中有新的规则加入时，Route Reflector 就会将新的记录同步

# 1. TyphaDaemon New 函数 #

NewClientV3 建立客户端连接，看着像 etcd，接着看看怎么使用的，github.com/projectcalico/libcalico-go/lib/backend/client.go 中定义了 backend.NewClient，可以使用 etcd 与 kubernetes

ConfigureEarlyLogging 配置日志

func New() *TyphaDaemon {
    	return &TyphaDaemon{
    		NewClientV3: func(config apiconfig.CalicoAPIConfig) (DatastoreClient, error) {
    			client, err := clientv3.New(config)
    			if err != nil {
    				return nil, err
    			}
    			return ClientV3Shim{client.(RealClientV3), config}, nil
    		},
    		ConfigureEarlyLogging: logutils.ConfigureEarlyLogging,
    		ConfigureLogging:      logutils.ConfigureLogging,
    		CachesBySyncerType:    map[syncproto.SyncerType]syncserver.BreadcrumbProvider{},
    	}
    }

#    2. InitializeAndServeForever 函数 #

DoEarlyRuntimeSetup 主要是前期设置日志格式以及日志级别，主要用于配置的日志记录

ParseCommandLineArgs 这个分析命令行参数，--config-file:/etc/calico/typha.cfg

>     [global]
>     MetadataAddr = None
>     LogFilePath = None
>     LogSeverityFile = None

LoadConfiguration 这个函数内容挺多，pkg/config/config\_params.go 中 结构体 Config，初始化使用了默认值，使用反射机制，字段非常多，如下一部分，从环境变量中 load 前缀为 typha 的 key，在从配置文件 /etc/calico/typha.cfg 中读取

>     DatastoreType string `config:"oneof(kubernetes,etcdv3);etcdv3;non-zero,die-on-fail"`
>     
>     EtcdAddr      string   `config:"authority;127.0.0.1:2379;local"`
>     EtcdScheme    string   `config:"oneof(http,https);http;local"`
>     EtcdKeyFile   string   `config:"file(must-exist);;local"`
>     EtcdCertFile  string   `config:"file(must-exist);;local"`
>     EtcdCaFile    string   `config:"file(must-exist);;local"`
>     EtcdEndpoints []string `config:"endpoint-list;;local"`

func (t *TyphaDaemon) InitializeAndServeForever(cxt context.Context) error {
    	t.DoEarlyRuntimeSetup()
    	t.ParseCommandLineArgs(nil)
    	err := t.LoadConfiguration(cxt)
    	if err != nil { // Should only happen if context is canceled.
    		return err
    	}
    	t.CreateServer()
    	t.Start(cxt)
    	t.WaitAndShutDown(cxt)
    	return nil
    }

###    2.1 CreateServer 函数 ###

创建以及配置服务组件，就是不启动

FelixSyncerByIface 调用 felixsyncer.New 创建 felix syncer，实现在 github.com/projectcalico/libcalico-go/lib/backend/sycersv1/felixsyncer/felixsyncerv1.go， 定义了一大队 watchersyncer.ResourceType，实例化 watcherSyncer，实现在 github.com/projectcalico/libcalico-go/lib/backend/watchersyncer/watchersyncer.go 中，具体待定分析

BGPSyncerByIface 调用 bgpsyncer.New 创建 bgp syncer，实现在 github.com/projectcalico/libcalico-go/lib/backend/syncersyv1/bgpsyncer/bgpsyncer.go，同样实例化 watchersyncer

// CreateServer creates and configures (but does not start) the server components.
    func (t *TyphaDaemon) CreateServer() {
    	// Health monitoring, for liveness and readiness endpoints.
    	t.healthAggregator = health.NewHealthAggregator()
    
    	// Now create the Syncer and caching layer (one pipeline for each syncer we support).
    	t.addSyncerPipeline(syncproto.SyncerTypeFelix, t.DatastoreClient.FelixSyncerByIface)
    	t.addSyncerPipeline(syncproto.SyncerTypeBGP, t.DatastoreClient.BGPSyncerByIface)
    
    }

**     2.1.1 addSyncerPipeline 函数**

calc.NewSyncerCallbacksDecoupler() 主要是将数据从 syncer 发给 validator，实现在 pkg/calc/async\_decoupler.go

calc.NewSyncerCallbacksDecoupler 主要是将数据从 validator 到 cache

snapcache.New 创建 snapshot cache，具体在第 3 章节讲解

func (t *TyphaDaemon) addSyncerPipeline(
    	syncerType syncproto.SyncerType,
    	newSyncer func(callbacks bapi.SyncerCallbacks) bapi.Syncer,
    ) {
    	// Get a Syncer from the datastore, which will feed the validator layer with updates.
    	syncerToValidator := calc.NewSyncerCallbacksDecoupler()
    	syncer := newSyncer(syncerToValidator)
    	log.Debugf("Created Syncer: %#v", syncer)
    
    	// Create the validator, which sits between the syncer and the cache.
    	validatorToCache := calc.NewSyncerCallbacksDecoupler()
    	validator := calc.NewValidationFilter(validatorToCache)
    
    	// Create our snapshot cache, which stores point-in-time copies of the datastore contents.
    	cache := snapcache.New(snapcache.Config{
    		MaxBatchSize:     t.ConfigParams.SnapshotCacheMaxBatchSize,
    		HealthAggregator: t.healthAggregator,
    	})
    
    	pipeline := &syncerPipeline{
    		Type:              syncerType,
    		Syncer:            syncer,
    		SyncerToValidator: syncerToValidator,
    		Validator:         validator,
    		ValidatorToCache:  validatorToCache,
    		Cache:             cache,
    	}
    	t.SyncerPipelines = append(t.SyncerPipelines, pipeline)
    	t.CachesBySyncerType[syncerType] = cache
    }

###    2.2 TyphaDaemon Start 函数 ###

p.Cache.Start 第 3.1 章节讲解

func (p syncerPipeline) Start(cxt context.Context) {
    	logCxt := log.WithField("syncerType", p.Type)
    	logCxt.Info("Starting syncer")
    	p.Syncer.Start()
    	logCxt.Info("Starting syncer-to-validator decoupler")
    	go p.SyncerToValidator.SendTo(p.Validator)
    	logCxt.Info("Starting validator-to-cache decoupler")
    	go p.ValidatorToCache.SendTo(p.Cache)
    	logCxt.Info("Starting cache")
    	p.Cache.Start(cxt)
    	logCxt.Info("Started syncer pipeline")
    }

2.2.1 从 syncer 发送给 validator 的 channel

func (a *SyncerCallbacksDecoupler) SendToContext(cxt context.Context, sink api.SyncerCallbacks) {
    	for {
    		select {
    		case obj := <-a.c:
    			switch obj := obj.(type) {
    			case api.SyncStatus:
    				sink.OnStatusUpdated(obj)
    			case []api.Update:
    				sink.OnUpdates(obj)
    			}
    		case <-cxt.Done():
    			logrus.WithError(cxt.Err()).Info("Context asked us to stop")
    			return
    		}
    	}
    }

###    2.3 syncserver Start 函数 ###

server 函数内容比较多，但是内容比较简单，处理请求，缓存连接 conn，最后调用 connection.handle 处理

func (s *Server) Start(cxt context.Context) {
    	s.Finished.Add(2)
    	go s.serve(cxt)
    	go s.governNumberOfConnections(cxt)
    }

2.3.1 connection.handle 函数

doHandshake处理握手请求，类型 MsgClientHello

sendSnapshotAndUpdatesToClient 异步发送 snapshot 更新

sendPingsToClient 定期的 ping-pong 请求

###    2.4 backend 后端为 kubernetes ###

if t.ConfigParams.ConnectionRebalancingMode == "kubernetes" {
    	log.Info("Kubernetes connection rebalancing is enabled, starting k8s poll goroutine.")
    	k8sAPI := k8s.NewK8sAPI()
    	ticker := jitter.NewTicker(
    		t.ConfigParams.K8sServicePollIntervalSecs,
    		t.ConfigParams.K8sServicePollIntervalSecs/10)
    	go k8s.PollK8sForConnectionLimit(cxt, t.ConfigParams, ticker.C, k8sAPI, t.Server)
    }
    log.Info("Started the datastore Syncer/cache layer/server.")

# 3. snapcache New 函数 #

>     Ctrie 中的每个节点都有一个和它相关联的同伴节点，当进行快照时，root节点都会被拷贝到一个新的节点，当树中的节点被访问时，也会被惰性拷贝到新的节点(持久化数据结构),这样的快照操作是常数耗时的。
> 
>     Ctrie 跟同步map或者跳跃表比起来，插入操作更耗时一些，因为寻址操作变多了。Ctrie真正的优势是内存消耗，跟大多的Hash表不同，它总是一系列在tree中的keys。**另一个性能优势就是它可以在常量时间内完成线性快照**。

func New(config Config) *Cache {
    	config.ApplyDefaults()
    	kvs := ctrie.New(nil /*default hash factory*/)
    	cond := sync.NewCond(&sync.Mutex{})
    	snap := &Breadcrumb{
    		Timestamp: time.Now(),
    		nextCond:  cond,
    		KVs:       kvs.ReadOnlySnapshot(),
    	}
    	c := &Cache{
    		config:            config,
    		inputC:            make(chan interface{}, config.MaxBatchSize*2),
    		breadcrumbCond:    cond,
    		kvs:               kvs,
    		currentBreadcrumb: (unsafe.Pointer)(snap),
    		wakeUpTicker:      jitter.NewTicker(config.WakeUpInterval, config.WakeUpInterval/10),
    		healthTicks:       time.NewTicker(healthInterval).C,
    	}
    	if config.HealthAggregator != nil {
    		config.HealthAggregator.RegisterReporter(healthName, &health.HealthReport{Live: true, Ready: true}, healthInterval*2)
    	}
    	c.reportHealth()
    	return c
    }

###    3.1 Cache Start 函数 ###

// Start starts the cache's main loop in a background goroutine.
    func (c *Cache) Start(ctx context.Context) {
    	go c.loop(ctx)
    }
    
    func (c *Cache) loop(ctx context.Context) {
    	for {
    		// First, block, waiting for updates and batch them up in our pendingXXX fields.
    		// This will opportunistically slurp up a limited number of pending updates.
    		if err := c.fillBatchFromInputQueue(ctx); err != nil {
    			log.WithError(err).Error("Snapshot main loop exiting.")
    			return
    		}
    		// Then publish the updates in new Breadcrumb(s).
    		c.publishBreadcrumbs()
    	}
    }

3.1.1 fillBatchFromInputQueue 函数

处理 Cache inputC channel，把类型为 update 的存入 pending，publishBreadCrumbs 处理 pending 的 update

// fillBatchFromInputQueue waits for some input on the input channel, then opportunistically
    // pulls as much as possible from the channel.  Input is stored in the pendingXXX fields for
    // the next stage of processing.
    func (c *Cache) fillBatchFromInputQueue(ctx context.Context) error {
    	batchSize := 0
    	storePendingUpdate := func(obj interface{}) {
    
    	log.Debug("Waiting for next input...")
    	select {
    	case obj := <-c.inputC:
    		log.WithField("update", obj).Debug("Got first update, peeking...")
    		storePendingUpdate(obj)
    	batchLoop:
    		for batchSize < c.config.MaxBatchSize {
    			select {
    			case obj = <-c.inputC:
    				storePendingUpdate(obj)
    			case <-ctx.Done():
    				log.WithError(ctx.Err()).Info("Context is done. Stopping.")
    				return ctx.Err()
    			default:
    				break batchLoop
    			}
    		}
    		log.WithField("numUpdates", batchSize).Debug("Finished reading batch.")

3.1.2 publishBreadcrumb

更新 master Ctrie 发布新的 Breadcrumb，其中包含只读  snapshot

# 4. watcherSyncer #

watcherSyncer 结构体实现了 api.Syncer 接口，两个方法，Start() 和 Stop()

// watcherSyncer implements the api.Syncer interface.
    type watcherSyncer struct {
    	status        api.SyncStatus
    	watcherCaches []*watcherCache
    	results       chan interface{}
    	numSynced     int
    	callbacks     api.SyncerCallbacks
    	wgwc          *sync.WaitGroup
    	wgws          *sync.WaitGroup
    	cancel        context.CancelFunc
    }

###    4.1 Start() 函数调用的 run 方法 ###

run 函数实现了主要的逻辑 syncer，首先发送 wait-for-ready 状态，等待连接到 datastore。目前有两个 watcherSyncer，felix 与 bgp。

对每一种 syncer 注册的 resourceType，也就是 watcherCache 中处理 run，第 5.1 章节讲解

// run implements the main syncer loop that loops forever receiving watch events and translating
    // to syncer updates.
    func (ws *watcherSyncer) run(ctx context.Context) {
    	log.Debug("Sending initial status event and starting watchers")
    	ws.wgws.Add(1)
    	ws.sendStatusUpdate(api.WaitForDatastore)
    	for _, wc := range ws.watcherCaches {
    		ws.wgwc.Add(1)
    		go func(wc *watcherCache) {
    			wc.run(ctx)
    			log.Debug("Watcher cache run completed")
    			ws.wgwc.Done()
    		}(wc)
    	}

###    4.2 watcherSyncer 处理 channel 中 results  ###

log.Info("Starting main event processing loop")
    var updates []api.Update
    for result := range ws.results {
    	// Process the data - this will append the data in subsequent calls, and action
    	// it if we hit a non-update event.
    	updates := ws.processResult(updates, result)
    
    	// Append results into the one update until we either flush the channel or we
    	// hit our fixed limit per update.
    consolidatationloop:
    	for ii := 0; ii < maxUpdatesToConsolidate; ii++ {
    		select {
    		case next := <-ws.results:
    			updates = ws.processResult(updates, next)
    		default:
    			break consolidatationloop
    		}
    	}
    
    	// Perform final processing (pass in a nil result) before we loop and hit the blocking
    	// call again.
    	updates = ws.sendUpdates(updates)
    }

###    4.3 processResult 函数处理 result channel ###

不采取立刻更新操作，分组发送 felix 更新，类型有 api.Update error api.SyncStatus

// Process a result from the result channel.  We don't immediately action updates, but
    // instead start grouping them together so that we can send a larger single update to
    // Felix.
    func (ws *watcherSyncer) processResult(updates []api.Update, result interface{}) []api.Update {
    
    	// Switch on the result type.
    	switch r := result.(type) {
    	case []api.Update:
    		// This is an update.  If we don't have previous updates then also check to see
    		// if we need to shift the status into Resync.
    		// We append these updates to the previous if there were any.
    		if len(updates) == 0 && ws.status == api.WaitForDatastore {
    			ws.sendStatusUpdate(api.ResyncInProgress)
    		}
    		updates = append(updates, r...)

# 5. watcherCache  #

主要是 results channel，无类型，只接收 error，api.Update，api.SyncStatus

// The watcherCache provides watcher/syncer support for a single key type in the
    // backend.  These results are sent to the main WatcherSyncer on a buffered "results"
    // channel.  To ensure the order of events is received correctly by the main WatcherSyncer,
    // we send all notification types in this channel.  Note that because of this the results
    // channel is untyped - however the watcherSyncer only expects one of the following
    // types:
    // -  An error
    // -  An api.Update
    // -  A api.SyncStatus (only for the very first InSync notification)
    type watcherCache struct {
    	logger               *logrus.Entry
    	client               api.Client
    	watch                api.WatchInterface
    	resources            map[string]cacheEntry
    	oldResources         map[string]cacheEntry
    	results              chan<- interface{}
    	hasSynced            bool
    	errors               int
    	resourceType         ResourceType
    	currentWatchRevision string
    }

###    5.1 watcherCache run 函数 ###

// run creates the watcher and loops indefinitely reading from the watcher.
    func (wc *watcherCache) run(ctx context.Context) {
    	wc.logger.Debug("Watcher cache starting, start initial sync processing")
    	wc.resyncAndCreateWatcher(ctx)

5.1.1 resyncAndCreateWatcher 函数，循环实现resync，直到成功完成了重新同步启动了watcher

// resyncAndCreateWatcher loops performing resync processing until it successfully
    // completes a resync and starts a watcher.
    func (wc *watcherCache) resyncAndCreateWatcher(ctx context.Context) {
    	// The passed in context allows a resync to be stopped mid-resync. The resync should be stopped as quickly as
    	// possible, but there should be usable data available in wc.resources so that delete events can be sent.
    	// The strategy is to
    	// - cancel any long running functions calls made from here, i.e. pass ctx to the client.list() calls
    	//    - but if it finishes, then ensure that the listing gets processed.
    	// - cancel any sleeps if the context is cancelled

5.1.1.1 如果没有版本，那就实行全部同步

// If we don't have a currentWatchRevision then we need to perform a full resync.
    	performFullResync := wc.currentWatchRevision == ""

5.1.1.2 实行全部同步

<table> 
 <tbody> 
  <tr> 
   <td><em><strong>syncer</strong></em></td> 
   <td><em><strong>resourcetype</strong></em></td> 
   <td><em><strong>实现路径</strong></em></td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>felix</td> 
   <td>configUpdateProcessor</td> 
   <td>github.com/projectcalico/libcalico-go/lib/backend/syncersv1/updateprocessors/configurationprocessor.go</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>felix</td> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
   <td>&nbsp;</td> 
  </tr> 
 </tbody> 
</table>

UpdateProcessor.OnSyncerStarting 主要是开关功能

client.List 从后端获取该资源，本文使用的是 kubernetes 后端

handleWatchListEvent 对每一 KV，调用 UpdateProcessor的 Process 方法，对于符合的则调用 handleAddedOrModifiedUpdate 更新 KV，其实就是往 channel 塞值 wc.results <- \[\]api.Update

if performFullResync {
    
    	// Notify the converter that we are resyncing.
    	if wc.resourceType.UpdateProcessor != nil {
    		wc.logger.Debug("Trigger converter resync notification")
    		wc.resourceType.UpdateProcessor.OnSyncerStarting()
    	}
    
    	// Start the sync by Listing the current resources.
    	l, err := wc.client.List(ctx, wc.resourceType.ListInterface, "")
    	
    	// Once this point is reached, it's important not to drop out if the context is cancelled.
    	// Move the current resources over to the oldResources
    	wc.oldResources = wc.resources
    	wc.resources = make(map[string]cacheEntry, 0)
    
    	// Send updates for each of the resources we listed - this will revalidate entries in
    	// the oldResources map.
    	for _, kvp := range l.KVPairs {
    		wc.handleWatchListEvent(kvp)
    	}
    
    	// We've listed the current settings.  Complete the sync by notifying the main WatcherSyncer
    	// go routine (if we haven't already) and by sending deletes for the old resources that were
    	// not acknowledged by the List.  The oldResources will be empty after this call.
    	wc.finishResync()
    
    	// Store the current watch revision.  This gets updated on any new add/modified event.
    	wc.currentWatchRevision = l.Revision
    }

5.1.1.3 从现在的版本进行 watch 操作

// And now start watching from the revision returned by the List, or from a previous watch event
    // (depending on whether we were performing a full resync).
    w, err := wc.client.Watch(ctx, wc.resourceType.ListInterface, wc.currentWatchRevision)

5.1.2 从 watch channel 同步数据

类型包括 新增 修改 删除 以及错误，主要是靠 handleWatchListEvent 处理，比较容易看懂，就是新增的更新删除的 KV 处理到 results channel，由 watcherSyncer 处理

case event, ok := <-wc.watch.ResultChan():
    	if !ok {
    		// If the channel is closed then resync/recreate the watch.
    		wc.logger.Info("Watch channel closed by remote - recreate watcher")
    		wc.resyncAndCreateWatcher(ctx)
    		continue
    	}
    	wc.logger.WithField("RC", wc.watch.ResultChan()).Debug("Reading event from results channel")
    
    	// Handle the specific event type.
    	switch event.Type {
    	case api.WatchAdded, api.WatchModified:

### 总结： ###

typha 启动从参数，环境变量，文件读取配置参数，创建后端连接（kubernetes / etcd）

注册了两个 pipeline，创建 felix bgp syncer，每一个都有注册了 resourceType

watcherCache，对 resource 进行同步，list watch，扔到 channel results

watcherSyncer 处理 channel results

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